Electric accumulator



invented improvements in or l-lelatiup, to

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lilmllllllllllllll UEllElOlEtllllll GARBUIL' ill W, m t i it anal intramural Gilt GLOUCESTER, ENGLAND.

ll'o Ilia-airing. Applicatlor filed Ilene 19,

f1. 0 all whom it may concern:

in the county of Gloucester, llnoglaud, l

Electric llccuinulators, oi which the lollowing is a specification.

Electric acciunulators oil? the ordinary type comprising lead electrodes inunei in a dilute solution of sulphuric acid, are liable, under certain circumstances, to become What is lznovvn as sulphated, which condition seriously interferes with their eiiiciency and proper "Working and may even in extreme cases, put them out oi": action.

For desulphating a sulphatcd' accu1nulater with the object oi? restoring; it to its normal Working condition, the lead electrode plates have sometimes been remover. from the accumulator cell and the solid sulphate oi? lead removed from the suriaces oi the pl ates, as by scraping, and Washing in Water or weal: sulphuric acid, or, in Where the sulphating is not very bad, the plates, havebeen subjected to prolonged char, inc

With a Weak electric current, the acid electrolyte still remainingin the cell. Also, it has been proposed to pass a very weal: elec tric current, say oi? a density of ii an to 25 ainperes per square metre of the l lrtace oi the positive electrode, at an F. l 1 7. 01. about two to three volts and for from four a to about three or more Weeks, accordto the state oi the electrodes, through the sulphated ole :roi While immersed in an, electrolyte consisting of 'very dilute solution. of suloh ate of pot; in, sodium or jl'lilt,9jl1tl,5l.llll1 it d by adding; to the ac" clim'uilator cell, after removing the ordinary acid electrolyte thereif'li'oni, very dilute solution oi sulphate of potassium, sodiuiu oi inagnesiiun, or of potassium or sodiiun carbonate, boratc or hydrocxide which becomes converted into an alkaline sulphate by reaction with the sulphuric acid remaining in the cell, the alkaline sulphate being slightly acid duringthe electrolytic treatment. These methods are expensive, troublesome,

take considerable time and are otherwise was. @eriol No. 569,428. A

desulphated in an easy, quick and economical manner by means of a current of the density ordinarily used for charging; the accuumlator and this, it desired, without rcmoving the electrodes from their cell.

For this purpose, the lead electrodes of an electric accuinulatmi' or the hind referred to, that have become sulphated, are first freed :lroru the dilute sulphuric acid electrolyte with which they had previously been used, and are then subjected to a desulphating treatment by passing an electriccul'rent through them Whilst immersed in a strong); solution of an alkaline hydroxide or peroxide, the current being of a dcns'ty such as ordinarily used for charg ung the acculators, the charging rate of. Which is about i one ampere for each eight to twelve square inches of electrode surface, at the ordinary charging; voltage of about two to three volts.

According to one Way of carrying out the invention, the sulphuric acid electrolyte is removed from the accumulator cell, and any deposited sulphate oil lead Washed out with Watenafter which the accumulator cell is charged With the alkaline desulphating liquid or electrolyte hereinbetore described and accumulator electrically charged, or else thawed and discharp'ed, in any o1? 1 ways and u or the chargp inn, oondioons ordina ily adopted as hereilllllGllUl'lj:iIllillGCl. to addition, the desulphat in liquid may be gently shaken or ated later cell, when anode l celluloid, as is usual,

being injurioi'lsly alibi-ted by the solution,

otherwise the solution could be of greater strength.

The desulphating liquid used may advantageously consist o't' an aqueous solution of sodium hydro: ;ide or of sodium peroxide, which, by reaction with the sulphate of lead on the electrode, under the conditions of electrical charging above refered to, will reduce the sulphate of lead and form peroxide of lead on the positive plates or electrodes and spongy metallic lead on the negative plat-es or electrodes, the resulting sulphate of the alkali used being dissolved in the solution which is at all times maintained in an alhaline conditon. The plates or electrodes will not he injuriously ati'eciied hy such a so id either before, during or after the el chargingreferred to.

a non the desulphatinp; treatment cone pleted Which can be readily determined, by inspection in the usual manner, the passage of an electric current is stopped and the resulting liquid removed from the cell and replaced with the usual dilute solution of sulphuric acid. Or the desulphating solution may be allowed to remain in the cell to constitute the exciting liquid in the subsequent working of the accumulator.

If desired, the sulphated plates or electrodes may be removed from the accumulator cell for treatment in a separate vessel with the desulphating liquid under the condition of electrical charging as above described. This treatment in a separate vessel is however not necessary tor successfully carrying out the invention.

What I claim is l. The method in" desulphating the su phated lead electrodes at an electric :u-vir muiator by first freeing them from the sniphur c acid electrolyte with which they have been used and then elcctricall' charging; them whilst immersed a strong SOllll'lOYl of an alizaline oxide the current being of a density such L s ordinarily used for charging the accumulator and the sohition being at all times maintainei'l in an allcaline condition. suhstanially as de:-;cril -ed.

:2. The method oi? dcsulphatiiuy the sulphated lead electrodes of an elm-trir accumulator by first freeing; them from the sulphuric acid cleeti-otvte with which the have been used and then clot-tra ail charging thei'u whilst immersed in a strong: solution oi" an alkaline hydroxide.

In the method of dcsulphating sulphated lead electrtules according! to claim I the en'iployment as the desulphating liquid. oil? a strong; soltuiou of an oxide salt of sodium, subs antially as (,lcscrilu-ul.

at. In the method of desulphating sulphatcd lead electrodes according to cla m 1. the employment as desulpliatiug liquid, of a strong solution ot sodium hydroxide, sub stantially as descrined.

Signed at Cardili', \Vaics, this 1st day of June. 1922.

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